Athletic or other activewear shoes of a conventional construction generally have three or four separate parts. First, such shoes are provided with an outsole that is made of a durable material and that extends across the lower surface of the shoe. A midsole is joined to the outsole to provide a cushioning layer to the wearer's foot. Usually, an upper formed of leather, synthetics or other materials is joined to the midsole. In many conventional structures, an insole is further provided for disposal between the midsole and the wearer's foot for additional cushioning.
The midsoles of these conventional constructions have two undesirable characteristics. First, they have the property of deforming over a large area of surface when a downward force is impressed on them. Second, the midsoles are affixed to the shoes and therefore customers can make no choice in the midsole's cushionability without selecting another shoe. Thus, conventional midsoles do not offer anything in the way of independent suspension or deformation of various areas thereof, and further are suited to only a particular weight class or cushionability preference of wearers.
The need for a midsole having a plurality of cushioning elements, each demonstrating an individual suspension and deforming independently from the remaining elements has generally been met by the custom midsole as disclosed in U.S. Pat. No. 4,733,483, Mar. 29, 1988, to Lin. However, it has been found that a flat outsole and midsole as disclosed therein have a tendency to create a springboard effect which causes the heel to bounce and vibrate. Unless the midsole fits perfectly into the cavity created within the shoe, there is also a tendency for the midsole to slip therein. Thus, a need has arisen for a midsole that has a plurality of cushioning elements with individual suspension that does not slip or vibrate.